This invention relates generally to air dryers. More particularly, this invention relates to devices for removing moisture and contaminants from compressed air streams.
Compressed air is widely used in industry as an energy source. One problem associated with the use of compressed air is maintaining a relatively clean and dry supply of compressed air. For example, as atmospheric air is introduced into an air compressor, contaminants such as water vapor, dirt, particles, and oils and other lubricants associated with the compressor or the industrial setting can be introduced into the compressor. During compression, the temperature of the air increases, thus increasing the ability of the air to retain moisture. Normally, the compressed air is passed through aftercoolers and moisture separators, yet despite this the air can remain substantially saturated with oil and water and other contaminants. As the air travels through piping during use, the vapor condenses and creates corrosion. This can lead to expensive downtime and equipment failure. Accordingly, there remains a need in the art for improvements in the treatment of compressed air to dry it and otherwise remove contaminants.
The present invention is directed to a separator for removing contaminants from compressed air. In a preferred embodiment, the separator includes an elongate enclosure having an inlet end and an opposite outlet end. The inlet end of the separator is in flow communication with a source of compressed air and the separator defines a first air flow path between the inlet and outlet ends of the separator and a second air flow path between the outlet end of the separator and a wall member positioned adjacent outlet end of the separator for being contacted by air exiting the outlet end of the separator. Air traveling in the first flow path undergoes a volumetric expansion and substantial change of direction as it exits the separator and enters the second air flow path and further undergoes a change of direction as it impacts the wall member.
In another aspect, the invention relates to a air dryer for treating an inlet stream of air to remove water vapor therefrom to provide a dehumidified outlet stream of air. In a preferred embodiment, the dryer includes an air inlet for introducing the inlet steam of air into the dryer and an air outlet for removing the outlet stream from the dryer. A heat exchanger associated with the dryer includes first and second discrete air flow paths. The first air flow path has an inlet end and an opposite outlet end with the inlet end of the first air flow path being in flow communication with the air inlet. The second air flow path includes an inlet end and an opposite outlet end with the outlet end of the second air flow path being in flow communication with the air outlet and an opposite inlet end. An expansion channel is located within the dryer for expanding the flow of air exiting the first flow path. The expansion channel has an inlet end and an outlet end, the inlet end of the expansion channel being in flow communication with the outlet end of the first air flow path of the first heat exchanger. An evaporator is downstream of the expansion channel and includes a third air flow path and a refrigerant flow path. The third air flow path has an inlet end and an opposite outlet end with the inlet end of the third air flow path being in flow communication with the outlet end of the expansion chamber. The refrigerant flow path has an inlet end and an opposite outlet end. A refrigeration system is in flow communication with the refrigerant flow path of the evaporator for circulating refrigerant through the refrigerant flow path of the evaporator. A separator located downstream of the evaporator includes an inlet end and an opposite outlet end. The inlet end of the separator is in flow communication with the outlet end of the third air flow path. The separator defines a fourth air flow path between the inlet and outlet ends of the separator and a fifth air flow path between the outlet end of the separator and a wall member positioned adjacent outlet end of the separator. The wall member is located to be contacted by air exiting the outlet end of the separator. Air traveling in the fourth flow path undergoes a volumetric expansion and substantial change of direction as it exits the separator and enters the fifth air flow path and further undergoes a change of direction as it impacts the wall member. A demister is positioned in flow communication with the fifth air flow path and the inlet end of the second air flow path for receiving air traveling in the fifth air flow path and conducting it to the second air flow path for travel therethrough.
A significant advantage of the invention is that the dryer 10 of the invention remains effective to remove moisture and other contaminants over a wide range of flow rates. For example, the separator functions to remove contaminants by impaction and imparting Brownian Motion to contaminants, thus resulting in their separation from the flow of air. The demister further achieves separation by providing an environment wherein surface tension results in removal of contaminants from the air flow.